getChildren

Returns an unmodifiable list of all child tree nodes of the current tree node. Adding and removing elements is
not supported on the list. Adding new children should be done by the TreeModel.addChild(Object) method on the
tree node parent. Removing children should be done by the TreeModel.remove() method on the tree node itself.

getIndex

Returns the zero-based unique index of the current tree node. This is an underscore separated representation of
the position of the node in the tree hierarchy. The root node has index of null. The first child has
index 0. The second child of first child has index 0_1. The first child of second child
of third child has index 2_1_0.